A compromise measure designed to make it easier to prosecute police who commit reckless or negligent shootings in Washington was in trouble Tuesday after lawmakers realized their plans might violate the state Constitution.

Legislators in Olympia had been rushing to pass the deal, announced Tuesday, which would overhaul a controversial law that forces prosecutors to prove the officers acted with malice — a hurdle no other state has.

It passed unanimously out of the House Public Safety Committee in the morning. By late afternoon, though, some lawmakers were questioning the legality of process they planned, and an expected evening floor vote was scrapped.

The measure, Initiative 940, was initially proposed by activists outraged over questionable police shootings in Washington and across the country. They gathered enough signatures to pose it as an initiative to the Legislature.

Under the state Constitution, there are three ways the Legislature can respond to such an initiative: approve it as-is, in which case it becomes law; reject or ignore it, in which case it goes to the ballot the following November; or propose an alternative, which must appear alongside the original initiative on the ballot.

According to a 1971 analysis by the state Attorney General’s Office, any changes made to an initiative constitute an alternative proposal that must be sent to voters.

The compromise on I-940 was designed to keep it off the ballot, thus avoiding a costly and potentially divisive campaign. The activists with De-escalate Washington who proposed the initiative agreed to make some changes to it to win the support of law enforcement groups, who said they wanted to ensure the measure protects police who make honest mistakes.

Not every police group in the state backed the bill, but the Fraternal Order of Police, an influential union of front-line law enforcement officers, and other powerful police organizations are supporting it.

“Even though it isn’t perfect, it is a great outcome,” said Steve Strachan, executive director of the Washington Association of Sheriffs and Police Chiefs.

In an apparent attempt to satisfy the Constitution’s requirements, the sponsors of the compromise bill, Reps. Roger Goodman, D-Kirkland, and Dave Hayes, R-Stanwood, came up with an unusual plan: The Legislature would pass I-940 as is, and also pass the compromise bill, which would replace the initiative upon passage.

“We are not proposing an alternative to the initiative,” he said. “We are proposing a measure that would amend it after it is enacted by the Legislature.”

But the attorney general’s 1971 opinion appears to have closely addressed that scenario.

“Any such ‘corrective’ legislation would constitute an alternative proposal which would have to be submitted to the voters along with the original initiative itself,” the opinion said.